In the past, assignment of channels to cells of base stations in the fashion, which would ensure avoidance of interference impairing call quality required repeated interference measurements and expertise of network designers, which would allow for a correct interpretation of measurement results. In order to ensure avoidance of the interference, the PEGASOS software has been deployed, provided for determination of the plan of frequencies. The software supports assignment of channels to cells of base stations and the graphic presentation of the theoretical network range, the so-called network coverage, using mathematical models of propagation, digital terrain maps with the network structure superimposed thereon and the list of frequency channels, allocated to a given operator. In practise the theoretical computations do not always assure sufficient accuracy. Therefore, the authors of PEGASOS have released an additional source of corrective data, referred to as the Interference Optimisation Tool (IOT), including a real-life interference relation matrix. The IOT table is in fact a list of the minimum distances between frequency channels within pre-selected cells of base stations and those channels within another cell, which will interfere with them, should the distances between them be smaller than those provided in the table. In other words, the IOT table includes a list of channel restrictions, to be applied in order to avoid interference degrading call quality. Additionally, IOT channels restriction considered different quality requirements for specific GSM logical channels (BCCH, TCH) implemented on specific frequency channels. A network planner enters types of forbidden interference relations—defined in the PEGASOS specifications—into the IOT table using a dedicated interactive application and based on its experience in interpretation of the on-the-ground measurements. To date, we lacked a method for determination of the minimum distances between channels independent from a subjective assessment of a planner, i.e., which would be a reliable basis for a reliable IOT table.